The letter further notes on that issue, "[Melson] said that ATF was kept in the dark about certain activities of other agencies, including DEA and FBI. Mr. Melson said that he learned from ATF agents in the field that information obtained by these agencies could have had a material impact on the Fast and Furious investigation as far back as late 2009 or early 2010."

"The evidence we have gathered raises the disturbing possibility that the Justice Department not only allowed criminals to smuggle weapons but that taxpayer dollars from other agencies may have financed those engaging in such activities," Issa and Grassley noted.

According to the letter based on Melson's testimony Justice Department officials in the Office of the Deputy Attorney General (ODAG) have not been forthcoming with the congressional investigation. "Mr. Melson provided documents months ago supporting his concerns to the official in the ODAG responsible for document production to the Committees, but those documents have not been provided to us."

Melson has been acting director of ATF since April 2009. Before that he oversaw the Executive Office of U.S. Attorneys and held the office after the U.S. Attorney's scandal rocked the Bush Justice Department. Prior to that Melson was a long-time career prosecutor in the Eastern District of Virginia where he served as the top career official in the U.S. Attorney's Office.

Late Wednesday the Justice Department responded to the revealing letter that Reps. Issa and Sen. Grassley sent to Attorney General Eric Holder.

In the letter signed by Assistant Attorney General Ronald Weich the Department notes that Attorney Holder has requested an independent review of the Fast and Furious operation by the Department's Inspector General and that DOJ has made witnesses available for interviews on a voluntary basis.

"While we do not question the Committee's right to conduct appropriate oversight, we reject entirely any suggestion that our extraordinary efforts have been designed to limit- rather than facilitate- the Committee's access to information," Weich wrote.

Recently there have been several news accounts that officials were trying to oust Melson from DOJ. In their letter to Attorney General Holder the lawmakers who previously have been very critical of Melson and his tenure at ATF have changed their tune and urge the Attorney General to ensure Melson is not treated unfairly, "Given his testimony, unless a permanent director is confirmed, it would be inappropriate for the Justice Department to take action against him that could have the effect of intimidating others who might want to provide additional information to the Committees."